Why is Bob Marley missing a D string?

Question

I've seen lots of photos in which Bob Marley is missing the D string on his guitar, what purpose does this serve?

Answer 1

Maybe he doesn't like the D string (I don't like the high e string) so he decided to remove or to make some more room for his fingers.

Answer 2

A lot of his songs are played with a muted D string. It is just the way reggae sounds. I would suppose that rather than having to mute while he played, he just prefered to not use that string making more room for his fingers and making the upstroke clearer. I dont think he always played without a D string.